Method for bonding plastic micro chip

ABSTRACT

Disclosed is a method of bonding upper and lower substrates for manufacturing a plastic micro chip comprising the upper substrate, the lower substrate and a sample filling space having a predetermined height for filling a sample between the upper and lower substrates. According to the method, the upper and lower substrates are bonded by introducing an organic solvent between the upper and lower substrates. In addition, the invention provides a method of manufacturing a micro chip using the method and a micro chip manufactured according to the method. According to the invention, it is possible to easily and precisely bond the upper and lower substrates of the plastic micro chip.

This is a divisional of U.S. patent application Ser. No. 10/583,149,filed on Jun. 16, 2006, which is the U.S. National Phase application ofInternational Application No. PCT/KR2004/003337 filed on Dec. 17, 2004,which claims the benefit under §119 of Korean Application No.10-2003-0093443 filed on Dec. 18, 2003, the contents of each of whichare incorporated herein.

TECHNICAL FIELD

The invention relates to a method of bonding a plastic micro chip, andmore particularly to a method of bonding upper and lower substrates formanufacturing a plastic micro chip comprising the upper substrate, thelower substrate and a sample filling space having a predetermined heightfor filling a sample between the upper and lower substrates, wherein theupper and lower substrates are bonded by introducing an organic solventbetween the upper and lower substrates. In addition, the inventionrelates to a method of manufacturing a micro chip using the boningmethod and a micro chip manufactured according to the method.

BACKGROUND ART

Currently, researches and commercialization of a point of care (POC) anda lab-on-a-chip (LOC) (which means a laboratory on a chip and is atechnology for diagnosing various diseases in a small chip at a time)are actively carried out in a bio-industry. Typically, products allowingfor a rapid diagnosis and experiment as the POC or LOC are released as aproduct with a special surface treatment or reagent fixed in a plasticmicro chip or cartridge. It can be said that the cartridge or chip is acore of the product.

Generally, the plastic micro chip or cartridge used for the POC and LOCis made of polyethylene (PE) derivatives such as polycarbonate (PC),polystyrene (PS), polypropylene (PP) and polyethyleneterephthalate(PET), polymethylmethacrylate (PMAA) or an acryl based plastic, and isused as a disposable.

FIGS. 1 and 2 show a typical plastic micro chip used for alab-on-a-chip. Generally, the plastic micro chip comprises an uppersubstrate 16, a lower substrate 18 and a sample filling space (channel)10 having a predetermined height D or a fine structure, etc. between theupper and lower substrates.

It is required that the channel should be precisely manufactured to havea height of several μm to several hundreds μm when manufacturing theplastic micro chip. Accordingly, it is required to very precisely andcorrectly bond the upper and lower substrates including the channel orfine structure so that the plastic micro chip can perfectly function. Inaddition, surface properties of main parts of the cartridge or the chipshould be maintained as they are.

When manufacturing the plastic micro chip, the upper and lowersubstrates are generally bonded by a heat bonding, an ultrasonicbonding, an optical method or an adhesive using a primer.

The heat bonding method is mainly used to bond the material such as afilm. The optical method is a boding method using a specific molecularstructure of the plastic surface and can be applied to some plasticsonly. The method using the adhesive is used even in daily life. Theultrasonic bonding method is actively used in industries.

However, there are some disadvantages when bonding the plastic microchip using the above methods. In other words, there is a limitation incorrectly and precisely bonding the chip having the fine channel orstructure without an error, and it is difficult to bond the chip withoutinfluencing on properties of an inner surface thereof.

FIGS. 3 and 4 show a bonding process according to an ultrasonic bondingmethod of the prior art.

As shown in FIG. 3, a protrusion is formed on a lower surface of anupper substrate 16 and a recess is formed in an upper surface of a lowersubstrate 18. Then, when an ultrasonic wave is applied with the upperand lower substrates 16, 18 being overlapped, the protrusion of theupper substrate 16 is melted and thus the upper substrate 16 is bondedto the lower substrate 18. However, as shown in FIG. 4, since thebonding surface is irregular and rough, an empty space can be formed andit is difficult to control the channel to have a predetermined height(D), so that an error can occur.

Generally, in a plastic micro chip, the height of the channel should bealso precisely controlled in order to precisely manufacture a volume ofthe channel. However, it is difficult to precisely control the height ofthe channel with the prior bonding methods.

In addition, since the channel is not completely sealed and an emptyspace can be thus formed, a sample in the channel can flow out to theexterior and an air bubble can occur in the sample inside of thechannel.

DISCLOSURE OF INVENTION

Accordingly, the present invention has been made to solve theabove-mentioned problems occurring in the prior art. In the presentinvention, an organic solvent is introduced between an upper substrateand a lower substrate, and thus the substrates are easily and preciselybonded without an error when they are bonded.

The object of the invention is to provide a method of bonding the upperand lower substrates in order to manufacture a plastic micro chip usedfor a lap-on-a-chip (LOC), etc.

It is another object to provide a method of manufacturing a plasticmicro chip using the bonding method.

It is yet another object to provide a plastic micro chip manufactured bythe bonding method.

The invention relates to a method of bonding an upper substrate and alower substrate in order to manufacture a plastic micro chip.

More specifically, the invention relates to a method of bonding an uppersubstrate and a lower substrate in order to manufacture a plastic microchip comprising the upper substrate, the lower substrate and a samplefilling space having a predetermined height for filling a sample betweenthe upper and lower substrates, wherein the upper and lower substratesare bonded by introducing an organic solvent between the upper and lowersubstrates.

In addition, the invention provides a method of manufacturing a plasticmicro chip comprising an upper substrate, a lower substrate and a samplefilling space having a predetermined height for filling a sample betweenthe upper and lower substrates, comprising steps of:

(a) forming a fine channel space for filling a bonding organic solventin a bonding region of a circumference of the sample filling space; and

(b) overlapping the upper and lower substrates each other, and thenintroducing the organic solvent into the fine channel to bond the upperand lower substrates.

Preferably, one or more holes for introducing the organic solventcommunicating with the fine channel may be formed when the fine channelis formed in the step of (a).

After forming the fine channel, it may preferably to perform a corona orplasma treatment for the bonding area so that the organic solventsubsequently introduced smoothly flows and a bonding strength isincreased. The plastic micro chip having a functional channel has ahydrophilic surface or a functional group such as amine group, carboxylgroup or aldehyde capable of combining with a protein (for example,antigen, antibody or enzyme) or DNA. When the plasma treatment isperformed as described above, impurities are removed from the surface ofthe bonding region and a surface energy is increased, so that thesolvent can flow well. In addition, the bonding strength can beincreased. However, this treatment does not have influence on thesurface of the chip.

When forming the fine channel, the channel can become opaque if a heightof the channel is excessively high. Accordingly, it is preferred to foamthe fine channel so that the height thereof is not too high. Forexample, it is preferred to form the channel to have a height of about100 μm or less.

In addition, according to the invention, there is provided a plasticmicro chip comprising an upper substrate, a lower substrate, a samplefilling space having a predetermined height for filling a sample betweenthe upper and lower substrates, and a fine channel defining a space forfilling an organic solvent so as to bond the upper and lower substratesin a bonding region of a circumference of the sample filling space ofthe upper substrate.

Preferably, the plastic micro chip may comprise one or more holes forintroducing the organic solvent communicating with the fine channel. Thesolvent in the fine channel can smoothly flow by pressurizing ordecompressing the fine channel through the introducing hole.

According to the invention, the upper and lower substrates are made ofpolyethylene derivatives such as polycarbonate, polystyrene,polypropylene and polyethyleneterephthalate, polymethylmethacrylate oran acryl based plastic materials.

Any organic solvent capable of dissolving the material of the substratesmay be used in the invention. For example, ketone, aromatic hydrocarbon,halogenated hydrocarbon or cyanoacrylate compound or a mixture thereofis used. Especially, acetone, chloroform, methylene chloride,ethylcyanoacrylate or carbon tetrachloride or a mixture thereof ispreferably used.

BRIEF DESCRIPTION OF DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or similar components, wherein:

FIGS. 1 and 2 are a perspective view and a cross sectional view of aconventional plastic micro chip;

FIGS. 3 and 4 show a method of bonding an upper substrate and a lowersubstrate of a plastic micro chip according to the prior art;

FIG. 5 is a plan view of a plastic micro chip according to a firstembodiment of the invention;

FIG. 6 is a cross sectional view of the plastic micro chip in FIG. 5taken along line A-A′;

FIG. 7 is a cross sectional view of the plastic micro chip in FIG. 5taken along line B-B′;

FIG. 8 is a plan view of a plastic micro chip according to a secondembodiment of the invention; and

FIG. 9 is a cross sectional view of a plastic micro chip according to athird embodiment of the invention.

-- Description of reference numerals for important part of the drawings-- 100: plastic micro chip 120: upper substrate 140: lower substrate 10: sample filling space  12: sample introducing hole  14: sampledischarging hole  20: bonding region  30: fine channel  35: organicsolvent introducing hole D: height of sample filling space

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings. In the followingdescription of the present invention, a detailed description of knownfunctions and configurations incorporated herein will be omitted when itmay make the subject matter of the present invention rather unclear.

FIG. 5 is a plan view of a plastic micro chip 100 for bonding accordingto an embodiment of the invention. FIG. 6 is a cross sectional view ofthe plastic micro chip in FIG. 5 taken along line A-A′. FIG. 7 is across sectional view of the plastic micro chip in FIG. 5 taken alongline B-B′.

The plastic micro chip 100 comprises an upper substrate 120, a lowersubstrate 140 and a sample filling space 10 having a predeterminedheight (D) for filling a sample between the upper substrate 120 and thelower substrate 140. A sample introducing hole 12 is formed at a side ofthe sample filling space 10 and a sample discharging hole 14 is formedat the other side.

A fine channel space 30 having a height of 100 μm for filling a bondingorganic solvent is formed in a bonding region 20 of a circumference ofthe sample filling space 10. In addition, organic solvent introducingholes 35 communicating with the fine channel are formed at each of theapexes so that the organic solvent can be introduced into the finechannel 30.

Surfaces of the upper substrate 120 and the lower substrate 140 areplasma-treated so that an organic solvent (for example, acetone)subsequently introduced can flow well.

After that, in order to bond the upper substrate 120 and the lowersubstrate 140, the lower substrate 140 and the upper substrate 120formed with the fine channel space 30 are overlapped each other, and theacetone is introduced into the organic solvent introducing holes 35 ofthe fine channel 30 in a small amount (few μl). The acetone flows alongthe fine channel 30 by the capillary phenomenon, and melts the uppersubstrate 120 and the lower substrate 140 in the bonding region 20 ofthe periphery of the fine channel 30, thereby bonding them.

The acetone remaining in the fine channel 30 is rapidly evaporated intothe air, and the bonding region 20 is firmly bonded while sealing thesample filling space 10 without a bonding tolerance.

FIG. 8 shows a plastic micro chip having an enlarged organic solventintroducing holes 35 for easily introducing the organic solvent into thefine channel space 30.

FIG. 9 is a cross sectional view of a plastic micro chip according to athird embodiment of the invention. The plastic micro chip according tothe third embodiment of the invention includes recesses 30 formed ineach of side lower ends of the upper substrate 120. The upper substrate120 and the lower substrate 140 of the bonding region 20 can be bondedeach other by introducing the organic solvent into the recesses.

INDUSTRIAL APPLICABILITY

As described above, when the plastic micro chip is manufacturedaccording to the method of the invention, it is possible to preciselyand correctly bond the upper and lower substrates of the plastic microchip. Particularly, it is possible to perfectly seal the sample fillingspace (channel) of the plastic micro chip and to correctly manufacturethe channel having a desired height.

While the invention has been shown and described with reference tocertain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1-7. (canceled)
 8. A method for bonding a substrate, the methodcomprising: providing a first substrate; providing a second substrateover the first substrate, the first and second substrates defining afine channel; and introducing an organic solvent into the fine channelin order to bond the first and second substrates, the organic solventpropagating by capillary force into a bonding region defined by thefirst and second substrates, the bonding region being adjacent to thefine channel, wherein the first substrate and the second substrate arebonded to each other at the bonding region and define a sample fillingspace.
 9. The method of claim 8, wherein the fine channel has a heightand a width such that the organic solvent is made to propagate throughthe channel via only capillary forces without applying pressure on thefirst and second substrates in excess of that required to hold the firstand second substrates in place while the first and second substrates arebonded together using the organic solvent.
 10. The method of claim 8,wherein the first substrate includes a recess and the second substrateincludes a substantially planar surface, the fine channel being definedby the recess of the first substrate and the substantially planarsurface of the second substrate.
 11. The method of claim 8, wherein onlya few microliters of organic solvent are introduced into the finechannel.
 12. The method of claim 8, further comprising applying a plasmatreatment to the bonding region of the first substrate to facilitateflow of the organic solvent thereon.
 13. The method of claim 8, whereinthe fine channel has a height of approximately 100 μm or less.
 14. Themethod of claim 8, wherein the organic solvent includes ketones,aromatic hydrocarbons, halogenated hydrocarbons, cyanoacrylate compoundsor a mixture thereof.
 15. The method of claim 8, wherein the organicsolvent is acetone, chloroform, methylene chloride, ethylcyanoacrylate,carbon tetrachloride, or a mixture thereof.
 16. The method of claim 8,wherein the first and second substrates are comprised of polyethylenederivatives, polymethylmethacrylate, or acryl-based plastic materials.17. The method of claim 16, wherein the polyethelene derivatives includepolycarbonate, polystyrene, polypropylene, or polyethyleneterephthalate.18. The method of claim 8, wherein the bonding region separates a samplefilling space from the fine channel.
 19. A method for bonding asubstrate, the method comprising: providing a first substrate; providinga second substrate over the first substrate, the first and secondsubstrates defining a channel, a sample filling space, and a bondingregion provided between the channel and the sample filling space; andintroducing an organic solvent into the channel in order to bond thefirst and second substrates, the channel having a height and a widthsuitable for causing the organic solvent to propagate through thechannel via only capillary force.
 20. The method of claim 19, whereinthe organic solvent flows into the bonding region via only capillaryforce.
 21. The method of claim 20, wherein the first and secondsubstrates are held in place while the organic solvent propagatesthrough the channel and flows into the bonding region via only capillaryforce, the first and second substrates being held in place withoutapplying pressure on the first and second substrates in excess of thatrequired to hold the first and second substrates together while thefirst and second substrates are bonded using the organic solvent.